O potencial do resíduo do café como fonte de geração de energia
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Data
2022-08-26
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Universidade Federal de Viçosa
Resumo
O Brasil é o maior produtor e exportador de café do mundo e o estado de Minas Gerais, o maior produtor do país. Contudo, o processamento do café gera uma grande quantidade de resíduos, uma vez que mais de 50% do fruto do café é descartado, além da geração de borra de café após seu processamento e uso. Assim, a valorização dessa matéria orgânica por meio de processos avançados se torna necessária. Deste modo, o objetivo deste estudo foi determinar o potencial energético da casca e da borra de café, através da pirólise catalítica de cloreto de zinco e cloreto de magnésio e não-catalítica da casca de café e da pirólise e liquefação hidrotermal da borra de café. Para isso, a borra e a casca de café foram caracterizadas através de análise termogravimétrica, análise imediata, análise elementar e análise de poder calorífico superior. Para a pirólise catalítica do café, foi realizada a adsorção de 30 g de casca de café com 10% de cloreto de magnésio e cloreto de zinco. A pirólise da casca de café foi realizada a temperaturas de 350 e 500°C para cada ensaio. O maior poder calorífico superior obtido pela fração orgânica do bio-óleo foi obtido para a pirólise da casca de café sem aporte de catalisadores a 500ºC (34,8 ±0,00 MJ kg-1). Em relação ao balanço de energia, o processo de pirólise catalítica a 350ºC (Relação do consumo de energia (RCE) = 0,84) gerou mais energia que consumiu em comparação com o processo de pirólise sem aporte de catalisador na mesma temperatura (RCE = 0,94). Logo, a pirólise de casca de café com MgCl 2 a 350ºC se apresentou como o processo mais eficiente para a geração de energia. Em uma segunda etapa, foi realizada a pirólise da borra de café com um teor de umidade inicial de 5,94 ± 0,11 b.u. nas temperaturas de 350 e 500°C. Já a liquefação hidrotermal da borra de café foi realizada a um teor de umidade inicial de 66,97 ± 0,48% b.u. e temperatura de 350°C. O rendimento do produto sólido foi maior para a pirólise a 350 ºC (38,33%) enquanto o do bio-óleo foi maior para a pirólise a 500 ºC (45,29%). Na liquefação hidrotermal observou-se um maior poder calorifico superior da fração orgânica do bio-óleo (37,30 MJ kg-1) e uma menor relação de consumo de energia (RCE=0,39) em relação aos outros ensaios, significando que esse processo gerou mais energia que consumiu quando comparado com o processo de pirólise. Logo, a liquefação hidrotermal se apresentou como o processo mais eficiente para a geração de energia. Dessa forma, tanto a casca de café quanto a borra de café são biomassas promissoras para a geração de energia através dos processos termoquímicos estudados. Palavras-chave: Liquefação hidrotermal. Pirólise. Casca de café. Borra de café. Catalisador. Coffea arábica.
Brazil is the world's largest producer and exporter of coffee, and the state of Minas Gerais is the largest producer in the country. However, coffee processing generates amounts of waste since more than 50% of the coffee fruit is discarded, in addition to the generation of coffee grounds after its processing and use. Thus, the valorization of this organic matter through advanced processes becomes necessary. Therefore, the objective of this study was to determine the energy potential of the coffee husk through the catalytic pyrolysis of zinc chloride and magnesium chloride and non-catalytic of the coffee husk and the pyrolysis and hydrothermal liquefaction of spent coffee grounds. For this, the spent coffee ground and coffee husk were characterized by thermogravimetric analysis, immediate analysis, proximate analysis, and analysis of higher heating value. For the catalytic pyrolysis of coffee, adsorption of 30 g of coffee husk with 10% magnesium chloride and zinc chloride was performed. For each assay, the coffee husk pyrolysis was performed at temperatures of 350 and 500ºC. The highest high heating value obtained by the organic fraction of the bio-oil was obtained for the pyrolysis of the coffee husk without the contribution of catalysts at 500ºC (34.8 ±0.00 MJ kg -1 ). Regarding the energy balance, the catalytic pyrolysis process at 350ºC (RCE = 0.84) generated more energy than it consumed compared to the pyrolysis process without catalyst input at the same temperature (RCE = 0.94). Therefore, the pyrolysis of coffee husk with MgCl 2 at 350ºC was the most efficient process for power generation. In a second stage, the pyrolysis of the spent coffee grounds with an initial moisture of 5.94±0.11 b.u. at temperatures of 350 and 500ºC. Already the hydrothermal liquefaction of the spent coffee grounds was performed at an initial moisture of 66,97 0.48% b.u. and temperature of 350º C. The solid product yield was higher for pyrolysis at 350 ºC (38.33%), while that of bio-oil was higher for pyrolysis at 500 ºC (45.29%). The hydrothermal liquefaction observed a higher high heating value of the organic fraction of the bio-oil (37.30 MJ kg -1 ) and a lower energy consumption ratio (RCE = 0.39) compared to the other process, generating more energy than consumed when compared to the pyrolysis process. Therefore, hydrothermal liquefaction was the most efficient process for power generation. Thus, coffee husks and spent coffee grounds are promising biomasses for energy generation through the thermochemical procedures studied. Keywords: Hydrothermal liquefaction. Pyrolysis. Coffee husk. Spent coffee grounds. Catalyst. Coffea arábica.
Brazil is the world's largest producer and exporter of coffee, and the state of Minas Gerais is the largest producer in the country. However, coffee processing generates amounts of waste since more than 50% of the coffee fruit is discarded, in addition to the generation of coffee grounds after its processing and use. Thus, the valorization of this organic matter through advanced processes becomes necessary. Therefore, the objective of this study was to determine the energy potential of the coffee husk through the catalytic pyrolysis of zinc chloride and magnesium chloride and non-catalytic of the coffee husk and the pyrolysis and hydrothermal liquefaction of spent coffee grounds. For this, the spent coffee ground and coffee husk were characterized by thermogravimetric analysis, immediate analysis, proximate analysis, and analysis of higher heating value. For the catalytic pyrolysis of coffee, adsorption of 30 g of coffee husk with 10% magnesium chloride and zinc chloride was performed. For each assay, the coffee husk pyrolysis was performed at temperatures of 350 and 500ºC. The highest high heating value obtained by the organic fraction of the bio-oil was obtained for the pyrolysis of the coffee husk without the contribution of catalysts at 500ºC (34.8 ±0.00 MJ kg -1 ). Regarding the energy balance, the catalytic pyrolysis process at 350ºC (RCE = 0.84) generated more energy than it consumed compared to the pyrolysis process without catalyst input at the same temperature (RCE = 0.94). Therefore, the pyrolysis of coffee husk with MgCl 2 at 350ºC was the most efficient process for power generation. In a second stage, the pyrolysis of the spent coffee grounds with an initial moisture of 5.94±0.11 b.u. at temperatures of 350 and 500ºC. Already the hydrothermal liquefaction of the spent coffee grounds was performed at an initial moisture of 66,97 0.48% b.u. and temperature of 350º C. The solid product yield was higher for pyrolysis at 350 ºC (38.33%), while that of bio-oil was higher for pyrolysis at 500 ºC (45.29%). The hydrothermal liquefaction observed a higher high heating value of the organic fraction of the bio-oil (37.30 MJ kg -1 ) and a lower energy consumption ratio (RCE = 0.39) compared to the other process, generating more energy than consumed when compared to the pyrolysis process. Therefore, hydrothermal liquefaction was the most efficient process for power generation. Thus, coffee husks and spent coffee grounds are promising biomasses for energy generation through the thermochemical procedures studied. Keywords: Hydrothermal liquefaction. Pyrolysis. Coffee husk. Spent coffee grounds. Catalyst. Coffea arábica.
Descrição
Dissertação de mestrado defendida na Universidade Federal de Viçosa.
Palavras-chave
Coffea arabica, Pirólise, Casca de café, Borra de café, Catalisadores, Resíduos como combustível
Citação
FREITAS, Caroline Piccoli Miranda de. O potencial do resíduo do café como fonte de geração de energia. 2022. 97 f. Dissertação (Mestrado em Engenharia Agrícola) - Universidade Federal de Viçosa, Viçosa-MG. 2022.